JP2007288069A - Manufacturing method of semiconductor device - Google Patents

Abstract

Film characteristics are good and leakage current of a silicon nitride film can be further reduced.
A semiconductor device which forms a silicon nitride film on the surface of a silicon substrate by activating a gas containing nitrogen atoms with plasma and nitriding the surface of the silicon substrate with the activated gas containing nitrogen atoms. In this manufacturing method, the temperature of the silicon substrate 100 during nitriding is set to 600 ° C. or more, and a silicon nitride film having a thickness of 4.0 nm or more is formed on the surface of the silicon substrate 100.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which a silicon nitride film is formed on the surface of a silicon substrate.

As a material of a gate insulating film of a semiconductor element in a semiconductor logic, a DRAM gate, a flash memory tunnel gate, or the like, a silicon oxide film (SiO ₂ film) has been mainly used so far. However, since the dielectric constant of the SiO ₂ film is low, a method of nitriding the SiO ₂ film has been adopted in order to improve the dielectric constant.
According to this method, as shown in FIG. 6, a SiO ₂ film 15 which is an oxide film on a silicon substrate 10 and a SiON film which is an oxynitride film obtained by nitriding the SiO ₂ film 15 on the SiO ₂ film 15. 11 is formed.
However, there is a limit to the method for improving the dielectric constant by nitriding an oxide film, and a new approach is required.
Therefore, recently, a Si ₃ N ₄ film has attracted attention as a new approach. The dielectric constant of SiO ₂ is 3.9, whereas the dielectric constant of Si ₃ N ₄ is 7.0. Therefore, when the Si ₃ N ₄ film is applied to the gate insulating film, the physical film thickness can be doubled as compared with the conventional silicon oxide film, and in addition to the improvement of the dielectric constant, the leakage current can be greatly reduced. Because.

However, when the Si ₃ N ₄ film is formed by the thermal CVD (Chemical Vapor Deposition) method, the film starts from the island-like nuclei first, so it does not become a dense film, and the expected leakage current reduction effect is It was insufficient. Therefore, a plasma CVD method has been proposed in which N ₂ or NH ₃ gas is activated by plasma to nitride silicon (see, for example, Patent Document 1).
JP-A-2005-45028

  In addition, as another approach, research and development for applying high-k materials such as HfO having a high dielectric constant to the gate insulating film are actively carried out. There is a long way to go.

However, since the silicon nitriding method using plasma described in Patent Document 1 is processed by converting N ₂ or NH ₃ gas into plasma at a low temperature of 400 ° C. or lower, the surface of the silicon substrate is only about 2.0 nm. It was not possible to nitride, and the effect of reducing the leakage current of the silicon nitride film was not yet sufficient. In addition, because of nitridation at a low temperature, there are many defects in the film, and it is difficult to ensure good electrical characteristics of the semiconductor device.
An object of the present invention is to provide a method for manufacturing a semiconductor device that solves the above-described problems of the prior art and has excellent film characteristics and can further reduce the leakage current of a silicon nitride film.

  In the first invention, a silicon nitride film is formed on the surface of the silicon substrate by activating a gas containing nitrogen atoms with plasma and nitriding the surface of the silicon substrate with the activated gas containing nitrogen atoms. In the method for manufacturing a semiconductor device, the silicon substrate temperature during the nitriding treatment is set to 600 ° C. or more, and a silicon nitride film having a thickness of 4.0 nm or more is formed on the surface of the silicon substrate. is there.

A second invention is characterized in that, in the first invention, the gas containing nitrogen atoms is NH ₃ or N ₂ gas.

A third invention is characterized in that, in the second invention, a rare gas such as He, Ar, or Kr is added as a plasma assist gas to the NH ₃ or N ₂ gas.

  According to a fourth invention, in the first to third inventions, after the silicon nitride film is formed, the silicon substrate on which the silicon nitride film is formed is oxidized in a gas atmosphere containing high-temperature oxygen atoms of 850 ° C. or higher. The oxide film is formed by oxidizing the silicon nitride film and oxidizing only the interface between the silicon nitride film and the surface of the silicon substrate.

A fifth invention is characterized in that in the fourth invention, the gas containing oxygen atoms is one of oxygen gas, water vapor, and N ₂ O.

  According to a sixth invention, in the first to third inventions, after forming the silicon nitride film, oxygen ions are implanted into the interface between the silicon substrate surface and the silicon nitride film by an ion implant method, and the temperature is 850 ° C. or higher. An oxide film is formed at the interface between the silicon substrate surface and the silicon nitride film by annealing at a temperature.

  In a seventh aspect of the present invention, a mixed gas containing oxygen and nitrogen is activated by plasma, and the silicon substrate surface is subjected to an acid / nitridation treatment with the activated mixed gas, whereby a thickness of 4.0 nm is formed on the silicon substrate surface After forming the above-mentioned acid / nitride film, forming the acid / nitride film, a gas containing nitrogen is activated by plasma, and the acid / nitride is activated with the activated nitrogen-containing gas (nitrogen plasma). A silicon nitride film is formed on the surface of the silicon substrate by nitriding the film surface at a high concentration.

  According to an eighth invention, in the first to third inventions, a method of forming a silicon nitride film on the silicon substrate surface by nitriding the silicon substrate surface with the activated gas containing nitrogen atoms. A plasma processing apparatus having a processing chamber, a substrate support that supports the silicon substrate in the processing chamber, and a cylindrical electrode and a magnetic force line forming unit disposed around the processing chamber, and nitrogen atoms in the processing chamber The gas containing nitrogen atoms is activated by plasma discharge with a high-frequency electric field obtained by supplying high-frequency power to the cylindrical electrode and a magnetic field obtained by the magnetic force line forming means, By nitriding the surface of the silicon substrate with the activated gas (gas plasma) containing nitrogen atoms, the surface of the silicon substrate is nitrided. It is a method of forming a con film.

  A ninth invention is characterized in that, in the first to sixth and eighth inventions, the formed silicon nitride film is a gate insulating film of a semiconductor element such as logic, DRAM, flash memory or the like.

  According to the present invention, the film characteristics are good and the leakage current of the silicon nitride film can be further reduced.

Next, an embodiment of the semiconductor device manufacturing method of the present invention will be described.
A semiconductor manufacturing apparatus using plasma is used to implement a method for manufacturing a semiconductor device. There are several types of semiconductor manufacturing apparatuses using plasma depending on the plasma generation method. For example, inductive coupling type, capacitive coupling type, cyclotron type, magnetron type, etc. exist, but as an example of a plasma processing apparatus for carrying out the semiconductor device manufacturing method of the present invention, a deformation capable of generating high density plasma by an electric field and a magnetic field Description will be made using a magnetron type plasma processing apparatus (hereinafter referred to as an MMT apparatus).

  In this MMT apparatus, a substrate is installed in a reaction chamber that ensures airtightness, a substrate processing gas is introduced into the reaction chamber via a gas shower plate, the reaction chamber is maintained at a certain pressure, and a high-frequency is applied to the discharge electrode. Electric power is supplied to form an electric field, and a magnetic field is applied to cause magnetron discharge. Since the electrons emitted from the discharge electrode continue to circulate around the cycloid while drifting, the life becomes longer and the ionization generation rate is increased, so that higher density plasma than conventional capacitively coupled plasma processing equipment is used. Can be generated. The substrate processing gas is excited and decomposed by the high-density plasma to cause a chemical reaction to form a thin film on the substrate surface.

  FIG. 5 shows an MMT device 24 used in the embodiment of the present invention. The MMT apparatus 24 includes a vacuum container 28 that constitutes a processing chamber 26. The vacuum container 28 is configured by vertically joining an upper container 30 and a lower container 32. The upper container 30 is made of a ceramic such as alumina or quartz. The lower container 32 is made of metal. The periphery of the upper container 30 is covered with a cover 34. The upper container 30 has a cylindrical shape having a dome-shaped ceiling portion, and an upper lid portion 36 and a shower plate portion 38 are formed on the ceiling portion, and between the upper lid portion 36 and the shower plate portion 38. A diffusion chamber 40 is configured. An inlet 42 for introducing a processing gas is formed in the upper lid portion 36, a gas supply means (not shown) is connected to the inlet 42, and a number of nozzles 44 are formed in the shower plate 38. For example, two types of processing gases introduced from the introduction port 42 are mixed and diffused in the diffusion chamber 40 and supplied to the processing chamber 26 from the nozzles 44 of the shower plate 38.

  A susceptor 46, which is a substrate support for supporting the substrate W, is disposed in the lower central portion of the processing chamber 26. The susceptor 46 is provided with a resistance heater (not shown) for heating the substrate W. Further, the lower container 32 is provided with an exhaust port 48, and an exhaust means (not shown) such as an exhaust pump is connected to the exhaust port 48, so that after processing from the periphery of the susceptor 46 toward the bottom of the lower container 32. The gas flows, and then the processing gas in the processing chamber 26 is exhausted from the exhaust port 48.

  A discharge cylindrical electrode 50 is disposed around the processing chamber 26, that is, on the outer periphery of the upper container 30, by 1 to 3 mm away from the upper container 30. The cylindrical electrode 50 is connected to a high frequency power source 54 via an impedance matching unit 52. The high frequency power supply 54 generates high frequency power having a frequency of, for example, 13.56 MHz, and the magnitude of the power is adjusted in accordance with a control signal from the control device 56. Further, the magnetic force line forming means 58 is disposed around the processing chamber 26. The magnetic force line forming means 58 includes two permanent magnets 60 and 62 formed in a ring shape, is disposed around the processing chamber 26, and surrounds a space as a plasma generation region in the center of the processing chamber 26. The permanent magnets 60 and 62 are disposed at substantially upper and lower positions of the cylindrical electrode 50. The upper and lower permanent magnets 60 and 62 have magnetic poles at both ends (inner peripheral end and outer peripheral end) along the radial direction of the vacuum vessel 28, and the directions of the magnetic poles of the upper and lower permanent magnets 60 and 62 are set to be opposite to each other. ing. Accordingly, the magnetic poles at the inner peripheral portion and the magnetic poles at the outer peripheral portion are different from each other, and magnetic lines of force extending in the center direction from one permanent magnet 60 and returning to the other permanent magnet 62 are formed in the processing chamber 26. The

  The susceptor 46 described above is insulated from the lower container 32, and the susceptor 46 is grounded via a high frequency circuit (impedance variable circuit) 64. The high frequency circuit 64 can adjust the susceptor impedance in accordance with the control signal from the control device 56 described above.

  The high-frequency circuit 64 includes a coil and a variable capacitor, and the potential of the substrate W can be controlled via the susceptor 46 by controlling the number of coil patterns and the capacitance value of the variable capacitor.

  In the MMT apparatus 24 according to the embodiment of the present invention, a magnetron discharge is generated under the influence of the magnetic field of the permanent magnets 60 and 62, and charges are trapped in the space above the substrate W to generate high-density plasma. Then, the surface of the substrate W on the susceptor 46 is subjected to plasma nitridation processing or plasma oxidization / nitridation processing by the generated high density plasma. The start and end of the surface treatment is performed by applying and stopping high frequency power.

  When plasma nitriding or acid / nitriding is performed on the surface of the substrate W or the surface of the base film, the high frequency circuit 64 interposed between the susceptor 46 and the ground is controlled in advance to a desired impedance value. When the high-frequency circuit 64 is adjusted to a desired impedance value, the potential of the substrate W is thereby controlled, and a nitriding film or an oxynitriding film having a desired film thickness and in-plane film thickness uniformity can be formed.

Next, the operation of the MMT device 24 will be described. First, the substrate W is placed on the susceptor 46, and the gas in the vacuum container 28 is exhausted from the exhaust port 48 to make the inside of the vacuum container 28 in a vacuum state. Next, the susceptor 46 is heated to heat the substrate W. Next, the processing gas is introduced from the inlet 42. The processing gas introduced from the inlet 42 is diffused in the diffusion chamber 40 and supplied to the processing chamber 26 from the nozzle 44 of the shower plate 38. At the same time, high frequency power is supplied from the high frequency power source 54 to the cylindrical electrode 50. The high frequency circuit 64 is adjusted in advance to a desired impedance value. In the processing chamber 26, a high frequency electric field is formed by the cylindrical electrode 50, and magnetic lines of force are formed by the magnetic line forming means 58, so that a magnetron discharge is generated and the charge generated by the discharge is supplemented in the space above the substrate W. A high density plasma is generated. The substrate W on the susceptor 46 is processed by the generated plasma, and a plasma thin film is formed on the surface of the substrate W. After a predetermined time has elapsed, the supply of high-frequency power from the high-frequency power supply 54 is stopped, the gas in the vacuum vessel 28 is exhausted from the exhaust port 48, the substrate W on the susceptor 46 is taken out from the processing chamber 26, and the processing is terminated.
The gas pressure in the vacuum container 28 is determined by the flow rate of the processing gas introduced from the introduction port 42, the ability of a pump (not shown) connected to the exhaust port 48, and the exhaust conductance to the pump.

FIG. 4 is a schematic longitudinal sectional view for explaining a part of the structure of a flash memory showing an example of a semiconductor device manufactured by the method of manufacturing a semiconductor device according to the embodiment.
The flash memory 70 has a polymetal structure on a gate electrode (control gate). The flash memory 70 having a polymetal structure has a gate insulating film 115. The gate insulating film 115 includes an oxide film 105 made of SiO ₂ formed on the silicon substrate 100 to be an active layer, and a silicon nitride film 110 formed on the oxide film 105. The flash memory 70 further includes a floating gate 120 made of polysilicon (D-Poly-Si) formed on the gate insulating film 115, and SiO ₂ / SiN / SiO ₂ (ONO) formed on the floating gate 120. Structure), a polymetal gate 200 having a laminated structure as a gate electrode formed on the insulating film 130, and an etching stopper layer 180 made of a silicon nitride film formed on the polymetal gate 200, And a sidewall 170 formed on the side surface of the gate.
The polymetal gate 200 having the above laminated structure includes a gate electrode 140 made of Poly-Si, a barrier metal 150 made of tungsten nitride (WN) formed on the gate electrode 140 for the purpose of reducing resistance, and a barrier metal 150 And a metal thin film 160 made of tungsten (W).

  As described above, the gate insulating film of the flash memory 70 includes the oxide film 105 and the silicon nitride film 110. Specifically, the gate insulating film of the semiconductor element including the flash memory is manufactured as follows. .

[First Embodiment]
FIG. 1 shows a method for manufacturing a gate insulating film made of an oxide film and a silicon nitride film in the first embodiment. In this manufacturing method, a silicon substrate is plasma-nitrided and then thermally oxidized.
First, a field oxide film (LOCOS oxide film) (not shown) for defining an element formation region is formed on the upper surface of the silicon substrate 100. Next, impurities for adjusting the surface concentration are ion-implanted into the surface of the silicon substrate 100 in the element formation region (see FIG. 1A).

Next, a gas containing nitrogen atoms is activated by plasma, and the surface of the silicon substrate 100 is nitrided (plasma nitrided) with the activated gas containing nitrogen atoms, thereby forming a silicon nitride film on the surface of the silicon substrate 100. A Si ₃ N ₄ film 210 is formed (FIG. 1B).
In order to form the Si ₃ N ₄ film 210, the MMT device 24 described above is used. A gas containing nitrogen atoms is supplied by a high-frequency electric field obtained by supplying a gas containing nitrogen atoms into the processing chamber 26 and supplying high-frequency power to the cylindrical electrode 50 and a magnetic field obtained by the magnetic force line forming means 58. Is activated by plasma discharge, and the surface of the silicon substrate 100 is nitrided with the activated gas containing nitrogen atoms, thereby forming the Si ₃ N ₄ film 210 on the surface of the silicon substrate 100. By setting the temperature of the silicon substrate 100 during nitriding to 600 ° C. or higher and controlling the potential of the susceptor 46, a Si ₃ N ₄ film 210 having a thickness of 4.0 nm or more is formed on the surface of the silicon substrate 100. For example, by setting the peak-to-peak (V _PP ) of the susceptor potential to 500 V or more, the Si ₃ N ₄ film 210 having a thickness of about 6.5 nm can be formed on the surface of the silicon substrate 100.
For example, NH ₃ or N ₂ gas is used as the above-described gas containing nitrogen atoms. A rare gas such as He, Ar, or Kr may be added as a plasma assist gas to the NH ₃ or N ₂ gas.

For example, the conditions for plasma nitriding when N ₂ is used are as follows.
Gas: N ₂ = 1000 sccm
Pressure: 100Pa
Substrate temperature: 700 ° C
High frequency power: 300W

After an Si ₃ N ₄ film 210 as described above, in an atmosphere of a gas containing 600 ° C. or more hot oxygen atom, a silicon substrate 100 formed with the Si ₃ N ₄ film 210 is thermally oxidized, Si ₃ N ₄ The film 210 is not oxidized, and only the interface between the Si ₃ N ₄ film 210 and the surface of the silicon substrate 100 is oxidized to form a SiO ₂ film 205 as an oxide film (FIG. 1C). As the gas containing oxygen atoms, one of oxygen gas, water vapor, and N ₂ O is used. A dilution gas may be used for the gas containing these oxygen atoms.

For example, the conditions for the oxidation treatment when O ₂ is used are as follows.
Gas: O ₂ = 50 sccm
Pressure: 100Pa
Substrate temperature: 700 ° C

Next, the silicon substrate 100 on which the SiO ₂ film 205 and the Si ₃ N ₄ film 210 are formed is selectively removed by etching to form a silicon nitride film 110 and an oxide film 105 (FIG. 1D).

For example, in order to form the gate of the flash memory, after forming the Si ₃ N ₄ film 210 in FIG. 1C, a Poly-Si film, ONO structure insulating film, Poly-Si film, WN film, W A film and a Si ₃ N ₄ film are sequentially formed, selectively removed by etching to form a gate, a sidewall spacer film is formed on the entire surface, and then etched back to form a sidewall on the side surface of the gate. Then, ion implantation is performed using the gate and the sidewall as a mask to form source / drain regions, and the flash memory 70 shown in FIG. 4 is formed.

According to the method of manufacturing the gate insulating film according to the first embodiment described above, the temperature of the silicon substrate 100 during the plasma nitriding process is set to 600 ° C. or higher, so that an Si ₃ N ₄ film with few defects in the film is obtained. be able to.

Moreover, since so as to form a thickness of 4.0nm or more the Si ₃ N ₄ film on the silicon substrate 100, as compared with the Si ₃ N ₄ film having a thickness of 2.0 nm, Si ₃ formed on the silicon substrate surface The leakage current of the N ₄ film can be reliably reduced.

In addition, when such a process is performed, the oxygen component in the film increases and defects in the film tend to occur, but the silicon substrate surface is nitrided at a substrate temperature of 600 ° C. or higher compared to 400 ° C. By doing so, the oxygen component in the film can be greatly suppressed, the film can be made into a stable composition, and defects in the film can be reduced.
When the substrate temperature is set to 650 ° C. or higher, not only the oxygen component in the film can be suppressed to 25% or less, but also the film can have a more stable composition and defects in the film can be further reduced. In this case, nitrogen in the film is bonded to 100% silicon atoms, and there is no bond with unstable oxygen.

Further, in the present embodiment, even at the same substrate temperature (for example, 650 ° C.), a film nitrided with NH ₃ plasma gas has less oxygen component in the film than nitriding with N ₂ plasma gas, so Defects can also be reduced.
Moreover, if the silicon substrate surface is simply nitrided with plasma, a fixed charge is generated at the interface between the silicon and the nitride film, and the electrical characteristics of the device deteriorate, but in this embodiment, at the interface between the nitride film and the silicon substrate surface. Since the oxide film is formed, the fixed charges generated at the interface can be reduced, and good electrical characteristics of the device can be ensured.

In addition, when such a process is performed, the generation of plasma is particularly important. However, when a rare gas such as He, Ar, Kr or the like is added to the NH ₃ or N ₂ gas as a plasma assist gas, the generation of the plasma is further improved. Can promote.

In addition, when such a process is performed, the film composition of the SiO ₂ film is particularly important. When the gas containing oxygen atoms is any one of oxygen gas, water vapor, and N ₂ O, the silicon substrate An oxide film having a film composition closer to that of the SiO ₂ film can be formed at the interface with the device, and the mobility of the device is excellent.

  As described above, according to the first embodiment, an insulating film that can be nitrided with a thickness of 4.0 nm or more can be obtained. Therefore, the formed silicon nitride film can be used as a semiconductor such as a logic, DRAM, or flash memory. It can be used as a gate insulating film of an element, and good electrical characteristics of a device can be secured. In particular, when formed as a tunnel gate insulating film for flash memory, the dielectric constant of the nitride film is higher than that of a pure oxide film, and the physical film thickness can be increased even with the same electrical film thickness. Since the leakage current flowing through the film can be reduced, the reliability of the device can be greatly improved. Also, the writing speed can be increased.

In the first embodiment described above, after the Si ₃ N ₄ film is formed by nitrogen plasma, an oxide film is formed at the interface between the silicon nitride film and the silicon substrate surface by thermal oxidation. However, the present invention is not limited to this. For example, the following second and third embodiments may be used.

[Second Embodiment]
FIG. 2 shows a method for manufacturing a flash memory according to the second embodiment. The manufacturing method according to the second embodiment is different from the first embodiment in that the thermal oxidation treatment is performed after the plasma nitridation treatment, whereas the high temperature annealing is performed after the oxidation treatment by the ion implant method. This is different from the first embodiment.
After a Si ₃ N ₄ film 210 having a thickness of 4.0 nm or more is formed on the surface of the silicon substrate 100 by plasma nitriding (FIGS. 2A and 2B), oxygen ions O ⁺ are ion-implanted using the surface of the silicon substrate 100. And Si ₃ N ₄ film 210 are injected into the interface (FIG. 2C). After the implantation, annealing is performed at a temperature of 850 ° C. or higher to form a SiO ₂ film 205 at the interface between the surface of the silicon substrate 100 and the Si ₃ N ₄ film 210 (FIG. 2 (c ′)).

In the implantation step of FIG. 2C, for example, the conditions of the ion implant process when using O ⁺ are as follows.
Ion: O ⁺
Pressure: 0.1Pa
Substrate temperature: 100 ° C
Acceleration energy: about 2 KeV

Although it is difficult to deal with a shallow region by the ion implant method, according to the present embodiment, since a relatively thick Si ₃ N ₄ film can be formed on the silicon substrate surface, the silicon substrate surface and the Si ₃ N ₄ film can be formed. In the case of forming SiO ₂ at the interface with the film, it is possible to adopt an ion implant method that can easily cope with a deep region.

[Third Embodiment]
FIG. 3 shows a method for manufacturing a flash memory according to the third embodiment. The manufacturing method according to the third embodiment is different from that according to the first embodiment in that the thermal oxidation process is performed after the plasma nitriding process, whereas the nitriding process is performed after the plasma oxynitriding process. This is different from the embodiment.
A mixed gas containing oxygen and nitrogen is activated by plasma, and the surface of the silicon substrate 100 is subjected to an acid / nitridation treatment with the activated mixed gas, whereby a SiON film 208 having a thickness of 4.0 nm or more is formed on the surface of the silicon substrate 100. (FIG. 3B).

For example, the conditions of the plasma acid / nitriding treatment when O ₂ and N ₂ are used are as follows.
Gas: O ₂ = 50 sccm
Gas: N ₂ = 50 sccm
Pressure: 50Pa
Substrate temperature: 650 ° C
High frequency power: 300W

After the SiON film 208 is formed, a nitrogen-containing gas is activated by plasma, and the surface of the SiON film 208 is nitrided with the activated nitrogen-containing gas (nitrogen plasma) at a high concentration. A Si ₃ N ₄ film 210 is formed on the surface (FIG. 3C).

For example, the conditions of plasma nitriding when N ₂ is used are as follows.
Gas: N ₂ = 50 sccm
Pressure: 50Pa
Substrate temperature: 650 ° C
High frequency power: 300W

According to the third embodiment, since the mixed gas containing oxygen and nitrogen is activated by plasma, the gas containing oxygen and the gas containing nitrogen are activated by plasma, respectively, and oxidation treatment and nitriding treatment are performed. Compared with the case where it is performed in a separate process, one process can be omitted, and the process becomes easy.
Further, since the silicon substrate surface is nitrided by 4 nm or more in the depth direction, the leakage current of the Si ₃ N ₄ film formed on the silicon substrate surface can be surely reduced.
Further, since the SiON film surface is highly nitrided with nitrogen plasma after the SiON film is formed, the SiON film is left on the interface between the silicon substrate surface and the Si ₃ N ₄ film, and the SiON film is thick on the SiON film. A Si ₃ N ₄ film can be formed.

  The method for forming the gate insulating film in the method of manufacturing a semiconductor device according to the embodiment of the present invention has been described with respect to the case where an MMT device is used. However, as long as it does not depart from the scope of the present invention, other plasma source methods are used. A plasma apparatus is also applicable.

It is process drawing for demonstrating the manufacturing method of the gate insulating film in the 1st Embodiment of this invention. It is process drawing for demonstrating the manufacturing method of the gate insulating film in the 2nd Embodiment of this invention. It is process drawing for demonstrating the manufacturing method of the gate insulating film in the 3rd Embodiment of this invention. It is a schematic longitudinal cross-sectional view for demonstrating an example of the flash memory in embodiment of this invention. It is a schematic longitudinal cross-sectional view for demonstrating an example of the MMT apparatus in embodiment of this invention. It is a schematic longitudinal cross-sectional view for demonstrating the gate insulating film formed on the silicon substrate of a prior art example.

Explanation of symbols

100 silicon substrate 105 oxide film 110 silicon nitride film 205 SiO ₂ film 210 Si ₃ N ₄ film (silicon nitride film)

Claims (1)

In a method of manufacturing a semiconductor device in which a silicon nitride film is formed on a surface of a silicon substrate by activating a gas containing nitrogen atoms with plasma and nitriding the surface of the silicon substrate with the activated gas containing nitrogen atoms. ,
The silicon substrate temperature during the nitriding treatment is 600 ° C. or higher,
A method of manufacturing a semiconductor device, comprising forming a silicon nitride film having a thickness of 4.0 nm or more on a surface of the silicon substrate.

Images